There are two times where scripture says that they “came together” on the first day, and both of those times were at the end of the sabbath, in the evening, for Havdalah. One of those two times, it was really “the first of the weeks,” meaning the beginning of the weeks of pentecost.
Paul did tell his followers to come together on the first day of the week, but it was regarding money for Jerusalem.
Rather, "And upon the first day of the week, when the disciples came together to break bread." (Act 20:7)
As stated here , Regardless of whether the memorial feast was observed before or after midnight, one can be assured that it took place on Sunday, because it was “on the first day of the week” that the disciples met “to break bread.”
The reason that eating the Lord’s Supper after midnight would have been acceptable conduct for many Christians is because the Jewish method of counting time was still widely acknowledged. The Jews and the Romans used different standards for calculating the hours of the day, and although both systems split the day into two periods of twelve hours, a new day for the Romans began at midnight (cf. Pliny, n.d., 2:79), whereas a new day for the Jews began in the evening at sundown and lasted until sundown the following day. Luke, like Matthew and Mark, used the Jewish method of reckoning time in both his gospel account and in the book of Acts (cf. Luke 23:44; Acts 2:15; 23:23; cf. also John 19:14; 20:1,19).
Thus, Paul’s pre-midnight preaching corresponded to our Saturday evening, but was the beginning of their “first day.” Regardless of whether they observed the Lord’s Supper on the evening of the first day or the morning of the first day, it was observed on the proper day, the day on which Jesus rose from the grave (Luke 24:1)—the first day of the week.
Also they met,
1). To Mary, On the morning of the resurrection - Matthew 28:8-10; Mark 16:9; John 20:11-18
2). To two disciples going to Emmaus - Luke 24:13-33; Mark 16:12-13
3). To Simon (Peter) - Luke 24:31-35.
4). To the eleven disciples on the evening of Resurrection Sunday - Mark 16:14-18; Luke 24:36-44; John 20:19-23
5). To the Eleven disciples "Eight days later" - John 20:26-29
Pentecost happened on the first day of the week! The Church was born on the first day of the week! That doesn't make Sunday the Sabbath, it just tells you that after the resurrection of Jesus, the Sabbath is not emphasized.
When a day is mentioned in connection with the appearances of the risen Lord Jesus, it is always the first day of the week. Look at the extremely important events that occurred in the life of the first followers of Christ on the first day of the week.
1). Jesus startled them by appearing to them on the first day (John 20:19).
2). Jesus received worship from Thomas (John 20:27-28).
3). Sunday evening Jesus took bread and blessed it and broke it and gave it to His disciples evidently like He had in instituting the communion meal (Luke 22:19) and their "eyes were opened and they recognized Him" (Luke 24:31).
4). Sunday evening Jesus blessed His disciples twice saying "Peace be with you" (John 20:20; 26).
5). That same Sunday evening Jesus "...breathed on them and said, 'receive the Holy Spirit'" John 20:22.
6). On Sunday evening Jesus gave His disciples the ecclesiastical authority to proclaim forgiveness to those who believe in Him through the Gospel (John 20:23).
Not when you read it in the Greek....he didn't!
[I Corinthians 16:2] Κατὰ down/according to/as per (+acc), against (+gen) μίαν one (acc) { σαββάτων sabbaths (gen) ♦ σαββάτου sabbath (gen) } ἕκαστος each (of two) (nom) ὑμῶν you(pl) (gen) παρ’ beside (+acc,+gen,+dat) ἑαυτῷ him-/her-/itself (dat) τιθέτω let-him/her/it-be-PLACE-ing! , θησαυρίζων while TREASURE UP-ing (nom) ὅ τι who-/whom-/whichever (nom|acc) { ἂν ever ♦ ἐὰν if-ever } εὐοδῶται he/she/it-should-be-being-PROSPER-ed , ἵνα so that / in order to /because μή not , ὅταν whenever ἔλθω I-should-COME , τότε then { λογίαι collections (nom|voc); eloquent ([Adj] nom|voc) ♦ λογεῖαι collections (nom|voc) } γίνωνται they-should-be-being-BECOME/HAPPEN-ed .
Same example as I gave in post #49. Paul is speaking of the First Sabbath between Passover and Pentecost. He expected to stay in Ephesus until Pentecost (verse 8) so you can see the timeline.
μίαν σαββάτων does not mean "First day of the week"....no matter how much you wish to twist it. It means "First of the Sabbaths" and there were seven of them between Passover and Pentecost [Leviticus 23:15-16]. Paul speaks of the first one.